P-4 CPU upgrade

I have this great Intel 865 mobo/800 with a basic
2.4 CPU. With chips cheap these days, I got a
3.0/800 cheap. It boots fine in safe mode/network
and updates. Can't get it to boot to Windows??
Yes, it feels like it is running hotter. 6 case
fans. Ready to switch back to be sure it works.
Ideas???? thanks